This application claims the benefit of Taiwan application Serial No. 091116520, filed Jul. 24, 2002.
1. Field of the Invention
The invention relates in general to a dual-band antenna apparatus, and more particularly to a folded dual-band antenna apparatus
2. Description of the Related Art
As a result of the recent rapid advance of the wireless technology, mobile communication devices become much more popular than ever. For a mobile phone, one of the most popular mobile communication devices, size miniaturization and high communication quality are the basic requirements. Furthermore, superior dual-band characteristic, compact feature, and low manufacturing cost are also important elements for a mobile phone manufacturing industry.
The conventional antenna used for the mobile phone is an exposed linear monopole antenna. One of the drawbacks of it is that the exposed antenna can be easily broken and is inconvenient to carry. The extended antenna usually catches things unexpectedly. Furthermore, the manufacturing cost of the conventional antenna is high, and the application of the exposed linear monopole antenna in a dual-band or multi-band mobile phone makes the whole structure complicated. Thus, the conventional antenna cannot satisfy current demands, like miniaturization.
It is therefore an object of the invention to provide a folded dual-band monopole antenna with small size and low profile. In addition to foregoing advantages, the invention can protect the monopole antenna from damage, and increase the liability of the monopole antenna.
In accordance with the object of the invention, it provides a folded dual-band monopole antenna. The folded dual-band monopole antenna comprises at least a radiation body, a transmission line and a conductor. The radiation body resonates at a first operating frequency and a second operating frequency. The radiation body connects the transmission line by way of the conductor. The radiation body includes a first side and a second side corresponding to the first side. A number of slits are set alternately on the first side and the second side so that the radiation body is formed to be a meandered structure. In addition, a feeding point is set on the radiation body for defining a first current path and a second current path on the radiation body. The length of the first current path is a quarter of a wavelength corresponding to the first operating frequency, and the length of the second current path is a quarter of a wavelength corresponding to the second operating frequency.
It is noticed that the radiation body is folded along an extended direction of the slits to form as a pillar structure for size miniaturization. The radiation body can cover a surface of a pillar dielectric material structure by printing technology for further size miniaturization and improving the strength of the radiation body.